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WattUp Mini Will Not Save Energous


WattUp Mini performance is inferior to competing standards such as Qi.

Long-distance changing with the WattUp array pushed to 2017, performance downgraded.

Unless WattUp Mini generates significant revenue, WATT will need to raise more cash by Q2 2017.

In my previous article, I analyzed the Energous (NASDAQ:WATT) beam forming technology and the challenges that Energous faces in obtaining FCC approval for its high power WattUp array wireless charging technology. Specifically, I concluded that it is not possible to obtain 4 W power delivered over a distance of 6 feet within the established safety rules governing electromagnetic radiation. The article prompted Energous management to hold an emergency conference call to "provide a company update and address misinformation about the company's technology and direction." During the call, CEO Stephen Rizzone and CTO Michael Leabman spent some time discussing the high-power charging technology but the main emphasis was on highlighting the positive reception of the low power WATTUP Mini wireless charger introduced in 2016 CES.

In this follow-up article, I will first cover Energous' response to my earlier article and the recent developments in high power WattUp array technology. Next, I will analyze the performance and cost of the low-power WattUp mini charger.

Energous response to skepticism and recent WattUp demo

My earlier article prompted Energous to arrange a conference call to address my critique of the WattUp array technology. During the call, CTO Michael Leabman validated my analyses method but noted that:

1. It is possible to create pockets of energy near the WattUp array.

2. My limit for safe exposure (2 mW/cm2) is too low and higher emissions are acceptable. CTO Michael Leabman did not specify what he believes is the correct safety limit but power densities from WattUp array are higher.

3. My estimate for antenna efficiency was too conservative (50% vs 95%).

4. I had not factored in the transmitter and receiver antenna gains. I had assumed zero gain for the receiver antenna because I assumed that the charging should work no matter how the receiving device is oriented. (A technical note: The only way to have receiver antenna gain is to have a directional receiver antenna. This means that the receiver needs to be pointed directly to the transmitter.)

These points are further emphasized in the IEEE article where CTO Michael Leabman validates the use of Friis equation (doubling the distance gives 4x less power). In the IEEE demo, hundreds of milliwatts of power was delivered levels with the aid of directional antennas and high field densities (points 2 and 4 above). I will admit that this is a nice science demonstration.

The tone of the IEEE article was positive but problems emerge when one looks at the practical details: The power received from one WattUp array was less than 200 mW at 3-4 feet from transmitter. Even in this highly idealistic and controlled set-up, the power is 20 times less than in the UL test and it would take more than 10 hours to change a smartphone.

The biggest news, however, was that the receiver had to be perfectly oriented to the transmitter. As the article states, "it doesn't work nearly as well if the receiver antenna isn't parallel to (and pointed at) the transmitter." This is the price you pay for using directional receivers to obtain antenna gain to boost the power. The power output is higher but you need to perfectly orient your phone to charge it.

I can already envision the next iPhone advertisement with Energous technology inside: charge wirelessly (in 10 hours if within 3 feet of monitor sized array and phone must be upright pointing to the array). Recall the iPhone "antenna-gate" and Jobs' reply "don't hold it like that." Well, Energous' reply to customer issues might well be - don't put it on the table like that! Take away the orientation requirement for the receiver and the power level drops as much as 10x (=it will take 100h to change...